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Nanotechnogy Group Feature

Technology In Depth: Carbon Nanotubes

CARBON NANOTUBES
Nanotubes are the 1 dimensional wire form of a fullerene; the diameter is typically 1 to 5 nanometers (nm), while the length can be in the range of microns. Single-walled nanotubes (SWNTs) can be considered as a flat graphene sheet (Figure 2) cylindrically rolled into a tube. The tubes consist of two regions: the sidewall of the tube, and the end region of the tube.

A significant physical property of the CNT is the tube tip. Tube tips may be open ended or close capped. Closed tips are "capped" with a structure that is similar to one half of a C60 fullerene molecule. The sidewalls of CNTs consist of only hexagonal carbon rings, whereas the end caps are made of pentagons and hexagons in order for curvature to exist. Due to the symmetry of the cylindrical tube, CNTs have a discreet number of directions that can form a closed cylinder (Figure 2).

 
1
 
Figure 2: Graphene Sheet illustrating chiral arrangements


 
Two atoms in the sheet are selected as the origin, and when the sheet is rolled, the two atoms coincide with one another. The vector OA is known as the "rollup" vector, whose length is equal to that of the circumference of the nanotube. The tube is created so that point O touches point A, and B touches B´. The tube axis is perpendicular to the rollup vector. The chiral vector of the nanotube, OA, can be defined by
 
OA = nâ1 mâ2

where â1 and â2 are unit vectors in the two-dimensional hexagonal lattice, and n and m are integers.

Another important parameter is the chiral angle, Ø, which is the angle between Ch and â1. All nanotubes can be described as having:

 

 

0° <= ? <30°

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Press Box

 

 

 

EOSL scientists are growing carbon nanotube towers atop photovoltaic cells to produce longer lasting, more efficient solar power for compact electronic devices in the field.

 

 

Nanomanhattan compact 3D solar cells boost efficiency while reducing size, weight, and complexity of photovoltaic arrays.

 

 

Researchers develop the manufacturing technology to produce electrical devices from carbon nanotubes.

 

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